Winnie the Pooh in Mermaid Lagoon Theater is another upcoming Winnie the Pooh/Disney parks crossover film planned to be made by RatiganRules. It is unknown when the film will be made.
Ariel, Flounder, and other sea characters "swim" freely with Winnie the Pooh and his friends in this "undersea" theater, in a show featuring dazzling music and dynamic aerial performances. Here, Ariel and her undersea friends stand up to the evil sea witch Ursula and a few evil villains, in a musical performance of courage and friendship.
- Bloom, Stella, Flora, Musa, Tecna, Layla, Simba, Timon, Pumbaa, Sora, Mickey Mouse, Donald Duck, Goofy, SpongeBob SquarePants, Patrick Star, Genie, Percival C. McLeach, Ratigan, Fidget, the Grand Duke of Owls, and the Trix (Icy, Darcy, and Stormy) will guest star in this film.
- In this movie, Ursula gives a magic potion to McLeach that would turn Ariel back into a mermaid as part of their revenge plot to eliminate her. With help from Pooh and his friends, Ariel will have to defeat Ursula, McLeach, and their villain recruits to order to become human to be with Prince Eric again.